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About The Author My name is Mazli Mehr, I am eight years old, and go to CatUn Gabel school. 1 love to draw, write and read at school, and on the weekends 1 love to practice my gymnastics, go to yoodoo doughnuts with my dad and practice my recorder for ftin, and for my music clcss.

This is me:

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Resources: Bridge Basics www.pbs.org/wgbh/buildingbig/bridge/basics.html How Bridges Work science.howstuffWorks.com/engineering/civil/bridge.htm/printable Portland Bridges www.bridgestories.com/bridge How Are Bridges Constructed? www.ehow.com/pr\nt/how-does-l4965199-how-br\dges-constructedhtml Different Types Of Bridges

www.swe.org/iac/lp/bridge_03b.html


Remember that bridges are very important to people lite you and me, can you imagine a world without bridges? When you see a bridge think about It what Kind is it? What is it called? 1 have talked about a few different Kinds of bridges, but there are still many more Do you still wonder about bridges? Well you can looK at the websites and booKs on the "resources" page.

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Truss Bridges Truss bridges have diagonal steel tubes and straight steel bars. Truss bridges also have piers like a beam bridge. A truss is a fVame that supports a bridge. A truss bridge is almost exactly like a bean bridges, except truss bridges have braces. You mighi think that is all the bridges, but there is one more 1 think 1 should tell you about. .

Arch Bridges Arch bridges have steel and concrete, and can have a span up to 800 feet. The ends on a arch bridge push the arch together to keep the arch -from spreading apart. This is a truss bridge

This is an arch bridge

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Chapter Three Different Bridges Beam Bridges Beam bridges have lots of prestressed concrete, which is concrete with strong metal cables inside. When weight goes down on a beam bridge there is compression above, and tension below, transferring loads to piers, a pier is a supporting structure, such as a pillarThere are horizontal beams that rest on pillars at either end of the bridge, which is why beam bridges are called beam bridges. Suspension Bridges Suspension bridges have shorter spans, but are still a little long. There height is a midspan of 220 feet, and their towers are about 210 feet. Suspension bridges also have cables. Suspension bridges are very flexible because of their cables. Suspension bridges take most time to construct because of their long cables and high supports. Suspension bridges suspend loads from their main cables. Cable stayed bridges have high towers, and are much cheaper than suspension bridges. Not having giant cables like a suspension bridge saves lots of steel. This is a suspension bridge

This is a beam bridge


Chapter Two Designing Bridges One bridge designer does not desigr all bridges, usually one bridge designer only designs one kind of bridge. Weather patterns affect the designs because if there was a storm the bridge could be affected. The use of the bridge that will be built also affects what kind of bridge will be made. Designing uses engineers and architects. Bridges have compression above, and tension below. Engineers have to design bridges so that the bridge can hold up many cars, trucks and more. If bridges could not hold up cars and trucks, the bridge would break and fall down with the cars, trucks and more. John A. Roebling is one of the most famous bridge designers. His best bridge is the Brooklyn Bridge in New York This is John A. Roebling


Chapter One The San Francisco Earthquake The San Francisco earthquake was on October 19,1989, it was 7.1 on the • richter scale. Which measures how big an earthquake is. During that time the Bay bridge broke. Lots of people had used the Bay bridge when it existed, so then those people had to find a new way to get to the other side, such as a boat or to go around. Now, on September 2,2013 a new bridge has opened to replace the old Bay bridge. This is the old Bay Bridge

This is the new Bay Bridge

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Introduction Do you know how important bridges are to the United States? Very important. Do you ever wonder how bridges are constructed, or prepared and designed? There can be many bridge cross ngs any day in the United States, up to three billion 1 That's about 12 crossings per personl If we did not have bridges we would have to go around water or take boats like ferries. All bridges are constructed differently and with different supplies. Preoaring bridges takes several people like engineers, seismologists, surveyors, highway planners and geologists. A seismologist is a scientist who studies earthquakes. A geologist is a scientist who studies the earth. Bridges help lots of people like you, so dont you want to learn more about them?


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